Relationship between clinical features and blood levels of pentachlorodibenzofuran in patients with Yusho

Background: Yusho is a form of food poisoning that occurred in 1968, as a result of consuming rice bran oil contaminated with polychlorinated biphenyls (PCBs) and various dioxins such as polychlorinated dibenzofurans (PCDFs). The victims of Yusho suffered from various dermatological, ophthalmological, and mucosal symptoms in addition to general fatigue, weight loss, anorexia, headache, paresthesia of the extremities, abdominal pain, cough and sputa, dysmenorrhea, and growth retardation in infants and children. We measured the blood levels of dioxins in the annual medical check-up of Yusho patients from 2001 to 2003. Purpose: To analyze the relationship between the concentrations of PCDFs/ PCBs and the subjective/objective/laboratory findings of patients with Yusho. We also compared the present clinical findings with those collected in 1988. Results and discussion: The mean blood level of 2,3,4,7,8- pentachlorodibenzofuran (PeCDF) in 359 patients with Yusho was 177.50 pg/g lipids, which was much higher than that of normal controls (15.2 ± 8.9 pg/g lipids). The blood levels of PeCDF were significantly correlated with total PCB levels, hexachlorobiphenyl levels, urinary sugar, 2-h erythrocyte sedimentation rate, thymol turbidity test, and sodium levels. A significant correlation was also noted with dermatological findings (acneform eruption and comedones), mucosal findings (oral pigmentation), constipation, numbness in the extremities, body weight loss, and abnormal abdominal ultrasonography. The incidence and severity of most of the dermatological and ophthalmological symptoms decreased from 1988 to 2001-2003. In conclusion, high amounts of PCBs and PeCDF are still present in a number of patients with Yusho. The patients still suffer from various mucocutaneous and subjective symptoms.